7G50ME-B9.5
The MAN 7G50ME-B9.5 is a low‑speed, 2‑stroke marine main engine delivering 21 700 kW at 127 rpm, featuring camshaft‑driven exhaust valves and electronic fuel injection for high efficiency and Tier III emissions compliance.
Engine Specifications
Inspector Detail
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Designation decoded
7 stands for 7 cylinders, G for Green Ultra-Long-Stroke, 50 for 500 mm bore, ME-B for electronically controlled fuel injection with camshaft-controlled exhaust valve, 9.5 for Mark 9.5.
Background
The G50ME-B9.5 with 7 cylinders is the Green Ultra-Long-Stroke variant of the 50 bore class. S/B 4.6 for maximum efficiency. 7 cylinders for Handymax to Supramax power requirements.
Calculated metrics
Inspector checklist
- Cylinder liners: S/B 4.6 — extremely high side forces, thrust-side wear dominates
- Piston rings: Maximum side pressure — ring stability
- Alpha Lubricator: Calibration at 500 mm bore
- Crosshead bearing: Temperature across 7 cylinders
- Stuffing box: S/B 4.6 — monitor drainage
- Piston rod: Run-out
- ME-B control: Sensors and EICU
- Camshaft: Chain elongation
- Software updates
- Scavenge air box: Increased oil ingress risk with G-type
- Turbocharger: Single TC
- Exhaust temperature across 7 cylinders
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Exhaust temperature by cylinder | 350–420 °C at MCR | Spread >15 °C → check injection |
| Scavenge air pressure | 2.5–3.2 bar | Drop → TC/cooler |
| Pmax | ±2 bar cylinder balance | Deviation → control system |
| Cylinder oil feed rate | 0.5–0.8 g/kWh | Calibrate Alpha Lubricator |
Common Failure Modes
Expert tips
- 💡 7×G50ME-B9.5 with S/B 4.6: Torsional vibrations possible with 7 cylinders — ME-B control has Barred Speed Range configured, check vibration damper during inspection
- 💡 LDF (Load-Dependent Feed) in the Alpha Lubricator: Especially important with G-type — side forces vary strongly with load
- 💡 For VLSFO operation: BN40 cylinder oil with reduced feed rate, configure Alpha Lubricator accordingly
Related components
Classification & regulatory
IMO Tier II compliant. Tier III with EGR/SCR. EEDI-optimized. MARPOL Annex VI — VLSFO.
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 23
Components & Design
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Technical Data
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